<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 元素选择器1 */
        div {
            font-size: 30px;
        }
        
        /* 通配选择器0 */
        * {
            font-size: 12px;
        }
    </style>
</head>
<body>
    <div class="parent">
        <div class="child">font size</div>
    </div>
</body>
</html>